Between 1993 and 1997, 837 stray dogs from North Taiwan were necropsied and examined for dog heartworm infections. A thick smear from 20 ml of peripheral blood from each dog was also prepared and examined for microfilariae (mf). The overall prevalence of adult worms in the dog population was 57%. The prevalence of mf in 1228 house dogs from different parts of Taiwan was also determined from 20 ml of peripheral blood in the same way. The overall prevalence of mf was 25%, with a value of 30% in the main island of Taiwan, this being 15 times higher than that in the offshore islands (2%). In Taiwan, the prevalence ranged from 4% in Hualien County, East Taiwan, to 41% in Nantou County, Central Taiwan. The mf prevalences on offshore islands were 1% on Liuchiu and 2% on Lanyu. The mf density per 20 ml blood in 82 house dogs was found to be 23 mf per dog, with a range of 3–97 mf per dog. A total of 477 stray dogs were found to be infected with adult worms of Dirofilaria immitis. The mean number of 7 worms per dog was obtained, with a range of 1–55 worms per dog. These results indicate that the prevalence of canine dirofilariasis has increased in Taiwan over the past 10 years. Moreover, the prevalence may be related to the wind speed, temperature, relative humidity, and altitude in the different areas surveyed.

Demonstrating the equivalence of constructs is a key requirement for cross-cultural empirical research. The major purpose of this paper is to demonstrate how to assess measurement and functional equivalence or invariance using the 9-item, 3-factor Love of Money Scale (LOMS, a second-order factor model) and the 4-item, 1-factor Pay Level Satisfaction Scale (PLSS, a first-order factor model) across 29 samples in six continents (N = 5973). In step 1, we tested the configural, metric and scalar invariance of the LOMS and 17 samples achieved measurement invariance. In step 2, we applied the same procedures to the PLSS and nine samples achieved measurement invariance. Five samples (Brazil, China, South Africa, Spain and the USA) passed the measurement invariance criteria for both measures. In step 3, we found that for these two measures, common method variance was non-significant. In step 4, we tested the functional equivalence between the Love of Money Scale and Pay Level Satisfaction Scale. We achieved functional equivalence for these two scales in all five samples. The results of this study suggest the critical importance of evaluating and establishing measurement equivalence in cross-cultural studies. Suggestions for remedying measurement non-equivalence are offered.

The influences of temperature, cone height, and apex angle on the tensile and compressive behaviors of open-tip carbon nanocones (CNCs) under axial strains were examined. The tensile failure strain and failure load of the CNC were found to decline evidently as the system temperature increases. The average failure strain decreases with the growth in the cone height. Concerning compressive behaviors, the critical strain and critical load of the CNC reduce manifestly with the increase in the system temperature and the apex angle. As the cone height grows, the critical strain decreases evidently but the critical load has no obvious change. The buckling mode does not have much variation when the temperature increases. It displays a more distorted buckling pattern with the growth in the cone height and transfers from an axisymmetric pattern to an unsymmetrical and more warped pattern when the apex angle expands.

Postherpetic neuralgia (PHN) is the most common complication of herpes zoster (HZ). The aim of the present study was to compare the nutritional status of PHN patients with that of healthy controls, and then to identify risk factors for PHN using multivariate multiple logistic regressions. In the present cross-sectional study, we prospectively enrolled fifty PHN patients for at least 3 months and fifty healthy controls. We selected nine circulating nutrients including ionised Ca, Zn, retinol, folic acid, vitamin B12, vitamin C, α-tocopherol, γ-tocopherol and lycopene associated with both immunity and the modulation of neuropathic pain, and measured their concentrations in plasma/serum. Concentrations of ionised Ca, Zn, vitamin C and vitamin B12 were significantly lower in PHN patients than in controls after excluding those patients receiving supplements since the outbreak of HZ. The prevalence of either mild/marginal or severe deficiencies for any of the nine selected circulating nutrients in PHN patients (92 %) was much higher than that in controls (46 %) (P < 0·001). Lower concentrations of vitamin C ( ≤ 45·0 μmol/l), ionised Ca ( ≤ 1·05 mmol/l) and Zn ( ≤ 0·91 g/l) were found to increase independently the risk of PHN using binary variable (dichotomy) analyses with both PHN patients and controls in a multivariate logistic regression analysis. No significant correlations existed between the risks of PHN and the concentrations of retinol, folic acid, vitamin B12, lycopene or α:γ-tocopherol ratios. Thus, lower concentrations of circulating nutrients, namely vitamin C, ionised Ca or Zn, are probably a risk factor in Taiwanese patients with PHN.

Transmittance loops upon thermal cycling of VO2 thin films were found to change among films with different fabrication conditions that lead to different transition temperatures (Tts) from that of a strain-free VO2 single crystal, 68 °C. The residual stresses in the films quantitatively determined from x-ray diffractometry were used to explain this variation. Electron spectroscopy for chemical analysis spectra showed that the difference in the binding energy of core electrons 2p1/2 and 2p3/2 of the vanadium atom are affected by residual stress and proportional to Tts of the films. The bond length between vanadium and oxygen atoms at room temperature varies with different residual stresses and, furthermore, affects the movements of both atoms during phase change (and hence the Tt of VO2 thin films). Residual stresses also affect the hysteresis span of the transmittance loop. The relationship between the residual stress of as-deposited VO2 films and the relative positions between vanadium and oxygen atoms are also delineated in detail.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

VO2 is a material with reversible thermo-chromic properties. The reversible phase transition of a strain-free single-crystalline VO2, at a transition temperature (Tt) 68°C, is accompanied with changes in crystal structure, optical and electrical properties. With different processing conditions during thin film deposition, different transmittance loops will be resulted upon thermal cycling. The residual stress of the thin films with poor crystallinity, as determined from X-ray diffractometry, is found to be an important factor responsible for the Tt that increases with increasing residual stress. Residual stress affects the hysteresis span of the transmittance loop. The relationship between residual stress of as-deposited VO2 films and the relative positions between vanadium and oxygen under the residual stress are also delineated.

Low cost and reliability, optical storage media, in particular the CD-R, has become the main steam data storage media. This presentation is intended to discuss issues related to the CD-rewriteable technology and the longevity of the data stored.

The working principle of CDs can be subdivided into three major categories, the CD-ROM, CD-R and CD-RW. The CD-ROM is primary used for music and software distribution and is manufactured by injection molding process. in contrast, CD-R and CD-RW are storage media allows data storage by users. The manufacture process involves spin-coating a layer of photo-sensitive organic dye on a polycarbonate substrate, then over-coated with a refractive coating. Writing of the data bits was achieved by photo-bleaching processes, which change the absorption properties of the dye. Considering the operation principle, there are many factors influence the reliability and storage life of the CD-R.

The vasculature of two recessive dwarf mutants, nana-1 (nal) (FIG 1) and nana-2 (na2) (FIG 2) of maize (Zea mays)were studied. All the plants used in this study were grown at the field station of University of Western Ontario, London, Ontario, Canada, in the summer of 2000. The specimens were fixed in methanol, serially sectioned with a razor blade using a specially made jig. The image was obtained by using a modified Acer 620T flat-bed scanner in liquid (Cheng et al., 2001). The optical sections were obtained by twophoton florescence microscopy using an Olympus Fluorview FL300 confocal microscope equipped with a Spectra-Physics Mai-Tai tunable ultra-fast Ti-sapphire laser. Excitation wavelengths was set at 780nm NIR with a pulse width of l00fs, <550nm autofluorescence was detected. Extended focus views were generated by using AutoQuant's AutoVisualize-3D™ software.

Different from the parallel arranged longitudinal vascular bundles commonly found in the internodes of wild type, nal/nalhas a complex stem vasculature (FIG 3)(Cheng et al., 2000a; 2000b).

The field number of the objective lens limits the field of view in a conventional compound microscope; even at very low magnification, the microscope does not allow observation of large pieces of specimen at once. This made the observation of organs and large pieces of tissue sections inconvenient. in the course of studying the development of maize stem, we encountered the need of digitizing large hand sections for 3D reconstruction. Splicing a series of images that are taken at different positions to form a montage is not acceptable, because the jointed image suffers from mismatch due to lens distortion. Considering the resolution needed in our study, one alternative is to use a consumer flatbed scanner designed for a personal computer. in order to adapt the conventional scanner for wet tissue scanning, an Acer 620TPC flatbed scanner, equipped with a trans-illuminator, was modified (FIG 1).

The non-linear nature of multi-photon fluorescence (FL) excitation, SHG and THG restricts the signal detecting volume to the vicinity of the focal point. As a result, the technology has intrinsic optical sectioning capability. The use of multi-photon fluorescence excitation also allows micro-fluorometry at high spatial resolution. Figure 1 shows a conventional optical micrograph of maize protoplasts, the time lapse fluorescence spectral change from a single chloroplast is shown in FIG 2. Under high intensity illumination, biological specimen not only emits fluorescence, but also generates harmonic emissions. in addition to the Ti-sapphire laser commonly used in multiphoton microscopy, the use of ultra-fast Cr-fosterite laser made simultaneous detecting two- and three-photon fluorescence, SHG and THG possible. in addition to the fluorescence signals generated by multi-photon excitation process, non-linear phenomena such as harmonic generation can also provide useful information about the structure and optical properties of a specimen (Kao et al., 2000). Simultaneous recording the spectral response in an image (x-y-λ) can provide insight about the nature of the signal.

Conventional histological sectioning and staining techniques produce tissue sections, by large, independent from each other (e.g. the staining intensity depends on the total stainable substance within the section, but not influence by the section above or below it). Although the hardness of the structure in a given section may influence the quality of the following sections, never the less, each physical section can be generally regarded as an independent sampling event. However, the image intensity and relative contrast in an optical section obtained from confocal or non-linear optical microscopy varies depending on the position of the section where it was obtained. Therefore, in sampling terms, optical sections are dependent sampling events. Artifacts caused by the geometry and optical properties (e.g. absorption, scattering, refractive index) of objects within a specimen can interfere the interpretation of the result and hinder the usefulness of three-dimension reconstruction. Figure 1 demonstrates intensity variation in confocal and multi-photon micrographs due to the geometry of the specimen. Depends on the absorption coefficient and path length of the illumination and the fluorescecent light, a solid spherical object produced a 3D data set, when reconstructed, resemble an inverted Chinese rice bowl. Figure 2 shows a 3D reconstruction of an Arabidopsis thaliana mesophyll protoplast; note only half of the spherical cell facing the illumination is imaged as shown in the cut-off view in FIG 3.

Cone-beam X-ray microtomography attracts increasing attention due to its applications in biomedical sciences, material engineering, and industrial nondestructive evaluation. Rapid volumetric image reconstruction is highly desirable in all these areas for prompt visualization and analysis of complex structures of interest. In this article, we reformulate a generalized Feldkamp cone-beam image reconstruction algorithm, utilize curved voxels and mapping tables, improve the reconstruction efficiency by an order of magnitude relative to a direct implementation of the standard algorithm, and demonstrate the feasibility with numerical simulation and experiments using a prototype cone-beam X-ray microtomographic system. Our fast algorithm reconstructs a 256-voxel cube from 100 projections within 2 min on an Intel Pentium II® 233 MHz personal computer, produces satisfactory image quality, and can be further accelerated using special hardware and/or parallel processing techniques.

There are number of dwarf mutants in maize such as d8, dl and nal. The nana plant 1 (nal/nal) is characterized as short erect dwarf; the phenotype does not respond to treatment of giberellins. The recessive nal allele is located on the long arm of chromosome 3 (3L-113). In this study, we report the abnormal development of the stem vasculature and the lack of clearly defined nodes.

Maize (Zea mays L., var. Ohio 43 and nal mutant) plants were grown in 1999 summer nursery at the fieldstation of University of Western Ontario, London Ontario, Canada. Plants at approximately 2 months old were fixed in 1:3 acetic acid/ EtOH. Multiple changes of fixative were made for a period of a month to remove as much pigmentation as possible. The specimen was then washed thoroughly, stained in diluted Schiffs reagent (10%), washed in 0.1M metabisulphate solution (with 1 ml of 1 N HC1 per liter), dehydrated in EtOH and cleared in methyl salicylate.

Pigeon liver malic enzyme was inactivated and cleaved at Asp141, Asp194, and Asp464 by the Cu2+-ascorbate system in acidic environment. Site-specific mutagenesis was performed at these putative metal-binding sites. Three point mutants, D141N, D194N, and D464N; three double mutants, D(141,194)N, D(194,464)N, and D(141,464)N; and a triple mutant, D(141,194,464)N; as well as the wild-type malic enzyme (WT) were successfully cloned and expressed in Escherichia coli cells. All recombinant enzymes, except the triple mutant, were purified to apparent homogeneity by successive Q-Sepharose and adenosine-2′,5′-bisphosphate-agarose columns. The mutants showed similar apparent Km,NADP values to that of the WT. The Km,Mal value was increased in the D141N and D194N mutants. The Km,Mn value, on the other hand, was increased only in the D141N mutant by 14-fold, corresponding to ∼1.6 kcal/mol for the Asp141-Mn2+ binding energy. Substrate inhibition by l-malate was only observed in WT, D464N, and D(141,464)N. Initial velocity experiments were performed to derive the various kinetic parameters. The possible interactions between Asp141, Asp194, and Asp464 were analyzed by the double-mutation cycles and triple-mutation box. There are synergistic weakening interactions between Asp141 and Asp194 in the metal binding that impel the D(141,194)N double mutant to an overall specificity constant [kcat/(Kd,MnKm,MalKm,NADP)] at least four orders of magnitude smaller than the WT value. This difference corresponds to an increase of 6.38 kcal/mol energy barrier for the catalytic efficiency. Mutation at Asp464, on the other hand, has partial additivity on the mutations at Asp141 and Asp194. The overall specificity constants for the double mutants D(194,464)N and D(141,464)N or the triple mutant D(141,194,464)N were decreased by only 10- to 100-fold compared to the WT. These results strongly suggest the involvement of Asp141 in the Mn2+-l-malate binding for the pigeon liver malic enzyme. The Asp194 and Asp464, which may be oxidized by nonspecific binding of Cu2+, are involved in the Mn2+-l-malate binding or catalysis indirectly by modulating the binding affinity of Asp141 with the Mn2+.

Due to the penetration ability and absorption contrast mechanism, cone-beam X-ray microtomography is a powerful tool in studying 3D microstructures in opaque specimens. In contrast to the conventional parallel and fan-beam geometry, the cone-beam tomography set up is highly desirable for faster data acquisition, build-in magnification, better radiation utilization and easier hardware implementation. However, the major draw back of the cone-beam reconstruction is its computational complexity. In an effort to maximize the reconstruction speed, we have developed a generalized Feldkamp cone-beam reconstruction algorithm to optimize the reconstruction process. We report here the use of curved voxels in a cylindrical coordinate system and mapping tables to further improve the reconstruction efficiency.

The generalized Feldkamp cone-beam image reconstruction algorithm is reformulated utilizing mapping table in the discrete domain as: , where .

Visualization is interdependent with gene mapping and DNA sequencing, because spatial relationships are important to understand function. The ability to visualize the chromosomes, especially in threedimensional (3D) space, has great benefits for the better understanding of a gene's function. For these reasons, a better technique is needed to study the chromosomes in 3D. Studying the stages of meiosis I provides an excellent opportunity to evaluate the capability of 3D imaging techniques. The loosening of the chromosomes in meiosis I exemplify the advantages of 3D imaging.

Tassel inflorescence from maize (Zea mays L., inbreed Ohio43) was collected from the field station at the University of Western Ontario in London, Ontario, Canada during the summer of 1998. Tassels at proper developmental stages were fixed in 3:1 (EtOH / acetic acid) solution. The anthers were stained with the Feulgen method and cleared in methyl salicylate.